Eat banana and drink protein supp on training days

I lift weights on every alternate days… eg. Mon/Wed/Fri and so on (not set to a weekly routine). And on the days off I’ll go for a run but not more then twice a week, worried about losing too much weight (180cm/72kg).

From reading posts here, I have come up with a very basic eating plan. I know there are a lot of technical protein information to consider but I really wanted something very easy:
Eat a banana and apple, or any other fruit but always make sure a banana is key. Do that 1 to 2 hours before hitting the gym and after drink a protein shake/formula/powder so I’d be only having the protein supplement every alternate day. No protein supp for running days or off days… is that good or bad?

My weight has remained at around 71.5kg – 73.5kg for the entire time I’ve been weight lifting (3 and a bit months). I have noticed a change in being a little more toned just not weight increase. After 3 months of training hard at the gym I was hoping for an increase of at least 2-3kg.

For what I want to do (lean muscle mass but not bulk mass) the lady at the supplement shop said I would be after a protein product that is low in carb, apparently there is low carb and high carb and a mid range when buying protein shakes. You guys would know all this stuff already.
This is the product I am think of having (someone on this forum recommended it)

I would have a scoop of protein with a banana an hour before and the same thing right after your workout with weights. opt to have a scoop of protein before cardio and a scoop with a banana after the cardio